水分胁迫对银水牛果生长及光合气体交换参数的影响

Influences of Water-stress on Shepherdia argentea Seedlings Growth and Photosynthetic Gas-exchange Parameters

实验以盆栽3年生银水牛果幼苗为材料，设置正常供水（W1）和轻度（W2）、中度（W3）、重度（W4）土壤水分胁迫共4个处理进行人工模拟实验，以探讨银水牛果的抗旱特征。结果显示，（1）随着水分胁迫的加剧，W2～W4银水牛果植株生长量较W1分别显著降低58．85％、72．06％、87．31％，地径生长量较W1分别显著降低38．46％、61．92％、84．62％；（2）随着水分胁迫的加剧，Pn日变化曲线由“单峰型”转为“双峰型”，且Pn、Gs、Tr，逐渐降低，L。值升高；（3）W3处理下Ci值最小，Ls值最大，而水分利用效率Ⅳ晒最高；（4）随着水分胁迫的加剧，Gs与Pn的相关性迅速下降，W2～W4的相关系数较W1分别下降5．06％、8．47％、24．38％；W4处理下Cs与Pn呈负相关。研究表明，银水牛果在土壤含水量为7．2％～14．35％干旱条件下水分利用效率最高，证明银水牛果具有较强的抗旱性。

In order to test the tolerance of Shepherdia argentea to drought conditions,we assigned four levers of soil water-stress treatments （normal water-stress treatments （W1）,low （W2）,moderate （W3） and severe water stress （W4） respectively to the 3-year-old Shepherdia argentea seedlings and simulated the water stress experiments. The results show that （1） with the increase of water-stress levels, Shepherdia argentea＇s longitudinal increment decrease remarkably by 58.85 % ,72.06 % and 87.31% respectively compared with W1,while their base diameter increment decrease by 38.46%,61.92% and 84.62% compared with W1 ; （2）With the increase of water-stress levels, the daily change curve of Shepherdia argentea ＇s photosynthesis rates （Pn） is gradually converted to bi-modal type from the uni-modal type and the values of Pn ,Gs and Tr decrease gradually while the value of Ls increases; （3）We observed the lowest Ci value,the highest Ls value and the best water use efficiency under W3 treatment; （4）With the increase of water-stress levels,Gs and Pn are less correlated with each other,with the coefficients dropping by 5.06% ,8.47% and 24. 38% compared with W1 ;Ci and Pn are negatively correlated under W4 treatment. In summary,our study shows that Shepherdia argentea has the highest water use efficiency in the soil which has a 7. 2%- 14. 35% water content and that Shepherdia argentea has strong tolerant ability to drought conditions.